Faucet mount filters for the treatment of drinking water are being increasingly used to treat water used for cooking and for drinking purposes. These devices ensure removal of a great variety of contaminants at the point of use. As the technology for removing a greater number of contaminants and impurities develop, these devices allow treatment of waters beyond that carried out by the municipal water treatment authorities as mandated by the United States Environmental Protection Agency under the Drinking Water Act of 1987. Increasingly there is recognition that the treatment of drinking water at the point of use is a more cost effective way to protect the population than treating huge quantities of water at the municipal level when only a fraction of that water is actually required for drinking and cooking, and recognizing that water used for other purposes, such as bathing or flushing toilets, does not need to be treated to the same extent as the drinking water.
With the growing popularity of faucet mounted filter devices, more convenient and consumer friendly devices are being created. Since the filter cartridge included in these devices has a limited capacity to remove the contaminant or contaminants, there is a need to indicate when the exhausted cartridge should be changed. This is accomplished by various mechanical and electronic indicators. In a typical faucet mounted filter there is a removable filter cartridge, an inlet connection, a tap water inlet passage, an unfiltered water outlet, a filtered water outlet, a passage between the filter and the filtered water outlet, a passage between the inlet passage and the unfiltered water outlet, and a valve selectively adjustable to direct unfiltered water to the unfiltered water outlet, or to the filter. Usually, a flow-reactive sensor is situated in the passage between the filter and the filtered water outlet. The flow-reactive sensor senses the flowing water and is connected to a signal generating element and power source. A signal generated by the flow reactive sensor is connected to a microprocessor, which interprets the data and activates either a time or event counter. There can also be a real time or event accumulator to accumulate the time or events during which the water flow occurs. The device may further contain a valve in communication with the power source and the signal processor, wherein the signal processor is configured to signal the valve when either the accumulated time or the event value for the water flow exceeds a set value. The device also may include a reset sensor in communication with the signal processor and positioned such that inserting a capacity rated filter cartridge in the device actuates the reset sensor. Alternatively the reset sensor could be manually altered to start again with a new filter cartridge element. The real time or event accumulator is in communication with the signal processor that is designed to activate an electronic digital indicator every time the flow event or time occurs. Further, the indicator device may be connected to two or more indicators that are activated depending on a predetermined use time or flow volume to give either early warning or intimation of complete exhaustion of the rated capacity of the filter cartridge. The flow reactive member may, for instance, be a turbine, and the signal-generating device may include a magnet or a pair of electrodes coupled with an electronic current sensing device. It can also include a pressure sensor.
The filter cartridges incorporated in faucet mounted filter devices are capacity rated to remove one or more contaminants. Since the media contained in these filters are specific to one or more contaminants, changing the media to treat other kinds of contaminants can result in a new capacity rating for the cartridge. A faucet mount device is usually able to accommodate a filter cartridge with only one capacity rating because its microprocessor is programmed to recognize only one capacity rating and resets to that one capacity rating because of the way it counts the event to zero rather than from zero. In other words, most faucet mounted filtering devices are currently configured to accept only one capacity rated filter cartridge and once reset they revert back to same capacity rating. Thus, such faucet mount devices can only be effectively used with a filter cartridge with a specific capacity rating. Filter cartridges with different specific capacity ratings require different filter devices. This is wasteful and expensive for the consumers.